There are common diseases that dogs get. There is a remedy to each one of these which your vet could easily prescribe to you or if you decide to take action yourself, there are many dog health books that you can obtain to read up on and handle your given situation.
It's always good to be aware of certain signs.
Some signs of an unhealthy dog are:
warm, dry nose
unusual discharge from the nose
eyes or any other body part
unusual sluggish behavior
doesn’t seem to want to eat it’s meal
limping, unusual lumps on the body
lack of balance
licking or biting a lot on a part of the body
darker colored teeth
dirty coat and difficulty getting up and lying down
difficult, abnormal or uncontrolled waste elimination
excessive weight loss or weight gain
These are not all of the signs but will help you to identify if your dog is having trouble.
Common Dog Diseases:
Kennel Cough - Dogs "catch" kennel cough when they inhale bacteria or virus particles into their respiratory tract. This tract is normally lines with a coating of mucus that traps infectious particles, but there are a number of factors that can weaken this protection and make dogs prone to kennel cough infection, which results in inflammation of the larnx (voice box) and trachea (windpipe).
If your dog is hacking away or constantly making noises that make it sound like he's choking on something, he may have a case of Kennel Cough, or canine infectious tracheobronchitis. Although kennel cough can sound terrible, most of the time it is not a serious condition, and most dogs will recover without treatment.
Canine Parvovirus - This is a highly contagious disease. It is common in an unvaccinated dog to contract parvo from the outdoor environment (streets, yards, etc). It can be transmitted by any person, animal or thing that comes into contact with an infected dog's feces. Highly resistant, the virus can live in the environment for months, and may survive on inanimate objects such as food bowls, shoes, clothing, carpet and floors.
Bloat/Gastric Torsion - Includes anxious behavior, depression, abdominal pain and distention, collapse, excessive drooling and vomiting to the point of unproductive, dry heaving. In looking further into a physical examination it may also reveal an extremely rapid heart beat (known as tachycardia), labored breathing (known as dyspnea), a weak pulse and a pale mucus membrane (the moist tissues lining the body's orifices, such as the nose and mouth.
Please have your dog checked as soon as possible by a Veterinarian if your dog has any of these symptoms.